Electricians use conduit to contain and protect internal wiring. The conduit is usually mounted on wall or ceiling structure. The mounting operation requires custom fitting of the conduit by bending, cutting and joining operations.
U.S. Pat. No. 6,088,407 issued to Parker shows a bending machine that is used in conduit-fitting operations. The bending occurs in a vertical plane coincident with an elongate axis of symmetry in the tubing or conduit. A spirit or bubble level attaches by use of a thumbscrew to an opening of the distal end of the conduit to assist with bending operations. The spirit level is positioned to sense level in a horizontal plane, i.e., a plane that is perpendicular to the plane of bending. Proper use of the spirit level in this manner assures that the conduit bends are aligned such that the bent conduit as a final product will fit flush against a planar wall or ceiling that ultimately supports the conduit in the intended environment of use.
U.S. Pat. No. 5,167,075 issued to Weldy et al. shows a different type of conduit-bending level. This device has two spirit levels. The level is shaped as a “T” where the body of the level is shaped and sized to slide into the mouth of a conduit opening. A first spirit level senses in the horizontal plane perpendicular to the plane of bending, similar to what is seen in respect to Parker's '407 patent discussed above. A second spirit level is provided that can exist coaxially with the elongate or longitudinal axis of the conduit. The positioning of this second spirit level facilitates us of a protractor arm assembly where the second spirit level indicates when bending is achieved with respect to a degree as set by the protractor arm.
Another type of conduit-bending level is shown in U.S. Pat. No. 4,272,208 issued to Yakkel. This device is designed to fit over the mouth of the conduit opening and contains two spirit levels. Both spirit levels are oriented perpendicularly to the elongate axis of the conduit.
A problem exists in the art where conventional conduit-bending levels are intended for use in bending conduit in a single plane. Thus, for example, if there is a need to bend conduit 90° in a first transition from horizontal to up along the plane of the wall, the bending level must be repositioned on the conduit to make a second bend in a direction that is perpendicular to the plane of the wall. This need sometimes arises where the conduit must proceed in a different orientation to run along the ceiling of a room or to bridge the connecting corners of two walls. When the bending level is repositioned for the second bend, it is difficult or impossible to re-orient the level to sense at a true 90° with respect to the first bend orientation.